Texture paint not working on sculpt Blender 2.8
There might be a new way to paint in 2.8 but for the moment your object doesn't have any material, so create a basic node chain like Image Texture (with your "main Okulossos Paint" image loaded) > Base Color input of a Principled BSDF > Material Output.

Now you still won't be able to paint, it's because you've opened a completely black texture for your brush, so close it and you'll have access to the normal color palet: